Coating apparatus

ABSTRACT

Apparatus for extruding a coating around a core including an extruder screw, stock feeder means operatively associated with the screw, and core coating means disposed adjacent the delivery portion of the screw; the stock feeder comprising pairs of opposed finger elements positioned to contact strip stock and means for sequentially moving the pairs of finger elements to engage the strip stock and to advance same into contact with the extruder screw; the coating means comprising a die having an opening therethrough, a guide member disposed within the opening forming a cavity through the die, means for withdrawing a coated core material from the die and means adjacent the core withdrawal means responsive to variations in the thickness of the coated core to control the withdrawal means.

United States Patent Klein Nov. 21, 1972 [54] COATING APPARATUS 923,3794/1963 Great Britain ..1 18/010. 18 [72] Inventor: Norman E. Klein,Inman, S.C. A Primary Exammer-James Kee Chi Asslgneel 38 NtlilllgellRseslrch Corpora- Attorney-Norman C. Armitage and H. William Petry ion,par an urg,

[22] Filed: Sept. 15, 1969 ABSTRACT v [21] L 35 ,094 Apparatus forextruding a coating around a core including an extruder screw, stockfeeder means operatively associated with the screw, and core coating[2%] (5|. ..l18/6,ll876g22?/1l/3(2, means disposed adjacent the deliveryportion of the E d o screw; the stock feeder comprising pairs of opposedr are 2 finger elements positioned to contact strip stock and means forsequentially moving the pairs of finger elements to engage thestripvstock and to advance same [56] References Cited into contact withthe extruder screw; the coating UNITED STATES PATENTS means comprising adieb having (21m openiLig therethrough, a guide mem er dispose within te git/23,; 1 opening forming a cavity through the die, means for 2834O475/1958 M y 226/162 X withdrawing a coated core material from the die and3,044,678 7/1962 st:;:l. e. 226/162 x means adjacent the core withdrawalmeans responsive FOREIGN PATENTS OR APPLICATIONS 921,414 3/1963GreatBritain ..ll8/DIG.18

to variations in the thickness of the coated core to control thewithdrawal means.

1 Claim, 5 Drawing Figures I I l P'A'TENTEunuvzl I972 3.703.154

sum 1 nr 3 I FIG.

INVENTOR. NORMAN,.E.KLEIN ATTORNEY PATENTEnnuvzl m2 3.703.154

SHEET 3 0F 3 INVENTOR.

, RMAN E KLEIN I Y n ATTORNEY COATING APPARATUS This invention relatesto apparatus for extruding a coating around a core, and moreparticularly relates to apparatus for automatically feeding strip stockto an extruder and apparatus for coating a core such as a reinforcingcord.

I in an extended position and vice versa. Each of the In the continuousextrusion of thermoplastic materials such as rubber, plastics, etc., oneof the problems is the necessity for maintaining an adequate supply ofthe feed stock. With extruders which utilize granular material, it iscustomary to maintain a supply of granules in a hopper and to gravityfeed them to the extruder. However, in the extrusion of rubber orsimilar materials, it generally is not practical to employ a granularmaterial, but instead, the feed stock customarily is in strip form.Since the strip stock is relatively tough and resists deformation, it isnecessary to apply a continuous positive force to the stock to insure anadequate supply to the feeder.

The present invention provides novel apparatus for extruding a coatingaround a core. Furthermore, the invention provides a new apparatus forcontinuously feeding strip stock to an extruder. Moreover, the inventionprovides novel apparatus for the coating of a core material such as acord.

The invention will be described in detail with reference to theaccompanying drawings in which:

FIG. 1 is a side elevation of one form of apparatus of the invention;

FIG. 2 is an enlarged sectional view taken along line 22 of FIG. 1;

FIG. 3 is an enlarged right end elevation of the apparatus shown in FIG.1;

FIG. 4 is a partial top elevation of the portion of the apparatus shownin FIG. 3; and

FIG. 5 is a further enlarged sectional view taken along line 5-5 of FIG.4.

As shown in the drawings, an extruder 11 has associated therewith astock feeder 12 and a cord coating portion 13. Extruder 11 has a screw14 (FIG. 2) which is driven through a gear box 15. The feeder 12 isoperatively connected to gear box 15 through shaft 16 and sprockets l7and 18 which are respectively disposed on shaft 16 and screw shaft 19.Sprockets 17 and 18 are interconnected by chain 20. Shaft 16 andsprocket 17 are connected by a clutch assembly including clutch plate21, thrust bearing 22, spring 23 and threaded nut 23a. The degree ofcompression of spring 23 by the adjustment of nut 230 provides aconstant torque which insures a uniform feed pressure of stock into theextruder 1 1.

The feeder 12 (FIG. 2) includes a feed chute portion 24 through whichstrip stock 25 is conveyed to funnel portion 26 and into contact withscrew 14. The feeder also includes pairs of opposed finger elements 27,27a, 28 and 28a. The pairs of finger elements are disposed adjacent theedges of the strip stock. The finger elements 27, 27a, 28 and 28a aresecured respectively to connecting rods 29, 29a, 30 and 30a. Connectingrods 29 and 30 are affixed to crank shaft 32 with each being mountedeccentrically to the other. Likewise, connecting rods 29a and 30a areaffixed to crank shaft 33 and mounted eccentrically to the other. Aspacial relationship between the respective connecting rods isestablished to position finger elements 27 and 27a in a retractedposition when finger elements 28 and 28a are finger elements has aprojection (34, 34a, 35 .and 35a) intermediate its length and adjacentthe internal cam surface of funnel 26. The projection serves asa raisedfulcrum which contacts the cam surface of funnel 26 during the operationof the feeder.

The cord coating portion 13 includes a cross head die 41 connected toextruder 11 by bolts 40 and movable with respect thereto on brackets 42and 43(FIGS. 3 and 4) which are pivotally affixed to each other withtheir opposite ends mounted on the extruder l1 and the die 41. Die 41(FIG. 5) includes a central guide member 44 and a coating sizing tip 45threaded into the lower portion of die 41. The upper portion of guidemember 44 is threaded to receive tapered nut 47 and lock nut 48. Guide44 has a longitudinal opening 49 for the passage of a cord therethrough.Set screws 51 are located in die 41 in an opposed quadrature arrangementto facilitate proper alignment of the guide 44. Proper positioning ofthe guide in the opening of die 41 forms a cavity 53 which connects tothe opening 54 in tip 45 and also communicates with a throat 56 adjacentthe bore 57 of the extruder 11.

A screen 58 is disposed over the end of bore 47 and maintained in properposition by collar 59 and a tapered perforated support 60. Die 41 has apassage 62 therethrough for the circulation of a heating fluid. Theguide member 44 is maintained in position within die 41 with cap screw61 and yoke 63 which presses against the upper surface of the guide. Theuse of a cap screw and'yoke facilitates the rapidremoval of the guidefor easy cleaning or other purposes. Proper repositioning of the guideis insured by set screws 51.

A guide roll 64 is mounted on bracket 6 5.above the opening 49 of guide44. Also, a driven grooved capstan 67 is disposed adjacent the opening54 of coating sizing tip 45 to draw the coated cord from the tip.

To control the thickness of the coating on the cord, a freely rotatableroller 68 is mounted on an arm 69 which pivots about shaft 70. Roller 68is biased against capstan 67 by strip spring 72 which is connected toarm 69 through link 73. Link 73 is pivotally attached to arm 69 by shaft74. Movement of rod 76 (FIG. 1) attached to one end of link 73 in turnmoves the armature of a linear variable differential transformer 77which is connected to an amplifier-controller (not shown).

In the operation of the apparatus of the invention, a cord 81 from asupply package 82 is passed over a series of guide rolls includingroller 64 and into the opening 49 of the guide member 44.Simultaneously, rubber stock 25 is passed through chute portion 24 ofthe feeder where the movement of fingers 27, 27a, 28 and 28a(hereinafter described) forces the strip stock into contact with screw14. Screw 14 forces the stock through bore 57 of the extruder pastscreen 58 and perforated support 60. The rubber stock then is forcedthrough throat 56 into cavity 53 where it contacts the cord 81 forming acoating thereon. Coated cord 81a is drawn from the tip 54 by capstan 67.

The strip stock 25 is forced into contact with the extruder screw 14 bythe cooperative action of finger elements 27 and 27a in combination withelements 28 and 28a. Rotation of crank shafts 32 and 33 moves fingers 27and 27a to a rear position with respect to the strip stock while fingers28 and 280 are in a forward position and vice versa as the crank shaftsrotate. The counter clockwise rotation of the shaft 32 and the clockwiserotation of the shaft 33 and the movement of connecting rods 29, 29a, 30and 30a resulting from such rotation, move the forward tips of fingerelements 27, 27a, 28 and 28a in elongated orbital paths approximatelyelliptical in shape. The tips of fingers 27 and 28 will orbit in aclockwise direction while the tips of fingers 27a and 28a will orbit ina counter clockwise direction. Crank shafts 32 and 33 are geared forsynchronous motion and timed so that forward and backward components ofthe motions of the tips of fingers 27 and 27 a are in the same directionand phase but transverse components are opposite in direction and phase.

Further rotation of the crank shafts causes the tips of the fingerelements to orbit as projections 34 and 34a contact the inner surface offunnel portion 26 as the finger elements move forward. Since the fingersare pinching the stock, the strip stock is advanced by this orbitalmotion of the finger tips into contact with the extruder screw 14. Whenthe fingers 27 and 27a reach their forwardmost point of travel, fingers28 and 28a disposed at the opposite side of the strip stock engage thestrip stock at a more rearward point. Additional rotation of the crankshafts 32 and 33 causes fingers 28 and 28a to move forward and theprojections 35 and 35a thereon to contact the upper cam surface offunnel 26 in the same manner as fingers 27 and 27a and thereby forceadditional quantities of the strip stock into contact with screw 14 andthe fingers are advanced in a forward direction. This pogo stick actionof the fingers 27 and 27a and fingers 28 and 28a is repeated alternatelywith a high degree of frequency to automatically and continuously feedthe strip stock into contact with the screw 14.

The thickness of the coated cord 81a is controlled by varying the speedof the capstan 67 which withdraws the cord from the die tip 45.Variations in the cord thickness change the position of roller 68 whichis biased against the cord and capstan 67. For example, if the cordbecomes thicker, roller 68 moves away from capstan 67 causing arm 69 topivot about shaft 70 and move link 73 which also is pivotally attachedthereto in a downward direction. Downward movement of link 73 causes rod76 to move an armature (not shown) downwardly in linear variabledifferential transformer 77. This movement of the armature intransformer 77 sends a signal to amplifier and control elements tochange the electric current to a motor (not shown in present inventionprovides a novel apparatus for ex- I truding a coating around a core.Also, the invention provides an automatic strip stock feeder tocontinuously feed rubber or plastic stock to an extruder. Moreover, thedesign of the stock feeder facilitates integration of the feeder withthe extruder due to its small size and space requirements. Further, thestock feeder provides positive feeding of the strip stock at all times.

In addition, the invention provides a new die design for coating a corematerial such as a reinforcing cord which does not require a bleed vent,thus minimizing rubber waste. Also, the die design provides ease ofopening for cleaning or other purpose. Furthermore, the apparatus of theinvention includes novel means for controlling the thickness of thecoating.

It will be apparent from the above description and drawings that variousmodifications may be made in the detailed designs and proceduresdescribed above within the scope of the invention. For example, aplurality of cords may be coated simultaneously. Also, the position ofthe feeder with respect to the rotation of the screw may be different.Therefore, the above descrip tion and drawings are intended toillustrate specific embodiments of the invention, and the scope of theinvention is to be limited only by the following claims.

That which is claimed is:

1. Apparatus for extruding a coating around a core including an extruderscrew, stock feeder means operatively associated with said screw, andcore coating means disposed adjacent the delivery portion of said screw;said stock feeder comprising pairs of opposed finger elements positionedto contact strip stock and means for sequentially moving said pairs offinger elements to engage said strip stock and to advance same intocontact with said extruder screw; said coating means comprising a diehaving an opening therethrough, a guide member disposed within saidopening forming a cavity through said die, means for withdrawing acoated core material from said die and means adjacent said corewithdrawal means responsive to variations in the thickness of saidcoated core to control said withdrawal means.

i =l= i

1. Apparatus for extruding a coating around a core including an extruderscrew, stock feeder means operatively associated with said screw, andcore coating means disposed adjacent the delivery portion of said screw;said stock feeder comprising pairs of opposed finger elements positionedto contact strip stock and means for sequentially moving said pairs offinger elements to engage said strip stock and to advance same intocontact with said extruder screw; said coating means comprising a diehaving an opening therethrough, a guide member disposed within saidopening forming a cavity through said die, means for withdrawing acoated core material from said die and means adjacent said corewithdrawal means responsive to variations in the thickness of saidcoated core to control said withdrawal means.